Red Blue is a Manga/Manhwa/Manhua in (English/Raw) language, ACTION series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Aoba, the hero who has walked the path of the shade. In order to push through the unyielding "feelings", he will jump into the world of mixed martial arts "MMA"-!!